A study on Multi-RAT (radio access technology) in which heterogeneous communication networks are managed in a manner of being integrated with each other has been performed. For example, a multi-RAT terminal supports both a cellular network and a wireless LAN. The multi-RAT terminal is able to selectively access a single RAT only among a plurality of RATs and is unable to access a plurality of the RATs at the same time. In particular, although a terminal has multi-RAT capability, the terminal is unable to transmit and receive data at the same time through RATS different from each other. In particular, it is necessary to newly define an interface configuration between network entities of RATs different from each other to support multi-RAT capability of a terminal.